The present invention generally relates to control circuits for reproducing transducer feeding motor in rotary recording medium reproducing apparatuses, and more particularly to a motor control circuit which controls the rotational drive of a motor for feeding a reproducing transducer of a reproducing apparatus along the radial direction of a rotary recording medium, according to the number of pulses applied to the above control circuit.
A new information signal recording system has been proposed in a U.S. Pat. No. 4,331,976 entitled "High Density Recording System Using Side-By-Side Information and Servo Tracks" issued May 25, 1982 of which the assignee is the same as that of the present application. According to this proposed system, the recording system forms pits in accordance with the information signal being recorded along a spiral track on a flat disc-shaped recording medium (hereinafter referred to as a disc), without forming a groove therein. In a reproducing system for reproducing the disc recorded by this proposed system, a reproducing stylus traces over along this track thereby to reproduce the recorded information signal in response to variations in electrostatic capacitance.
In this proposed recording system, since a groove for guiding the reproducing stylus is not provided on the disc, pilot or reference signals should be recorded on or in the vicinity of a track of the information signal, such as a video signal, on the disc. Upon reproduction, the reference signals are reproduced together with the video signal. Tracking servo control is carried out so that the reproducing stylus accurately traces along the track in response to the reproduced reference signals.
By use of this previously proposed system, there is no possibility whatsoever of the reproducing stylus or the disc being damaged since the recording track has no groove. The stylus can trace the same portion of the track repeatedly many times, whereby a special reproduction such as still, slow-motion, or quick-motion reproduction becomes possible.
Thus, in a U.S. Pat. No. 4,340,907 entitled "Special Reproducing System in an Apparatus for Reproducing Video Signals from a Rotary Recording Medium" issued July 20, 1982, of which the assignee is the same as that of the present application, a special reproducing system in a disc reproducing apparatus was proposed which is capable of performing a special reproduction in which a picture having a motion different from that upon normal reproduction is obtained in an excellent manner.
The special reproducing system comprises a reproducing element for tracing the track of the disc and picking up the recorded signal, a tracking control mechanism for operating in response to skip pulses applied thereto to cause the reproducing element to shift to an adjacent track turn of the spiral track thereby to undergo skipping, and a skip pulse generating circuit for generating skip pulses with timings corresponding to the vertical blanking period positions of the recorded video signal, where the skip pulses are of a number corresponding to an operational mode for carrying out a special reproduction differing from normal reproduction at every rotational period of the rotary recording medium, and supplying the skip pulses to the tracking control mechanism. The reproducing element is skipped to an adjacent track turn within the vertical blanking period of the recorded video signal, by the tracking control mechanism responsive to the skip pulses.
Accordingly, the noise introduced when the reproducing element moves to an adjacent track does not appear in the picture, and a special reproduction such as still reproduction, slow-motion and quick-motion reproduction in the forward direction, and normal-speed, slow-motion, and quick-motion reproduction in the backward direction can be performed in which a fine picture is obtained. Furthermore, the reproducing element can be moved or transferred at a high speed to enable a high-speed reproduction, by reproducing while performing tracking control with respect to a random access where the reproducing element is rapidly moved to a predetermined position, or with respect to the scanning of the tracks performed by the reproducing element.
Hence, it is necessary to move the reproducing transducer including the reproducing element at different speeds, according to each of the reproduction modes. Moreover, upon starting of the reproduction, it is necessary to mode the reproducing transducer from a waiting position to the starting position on the disc at a high speed, within a short period of time. Thus, it becomes necessary to variably control the moving speed of the reproducing transducer, according to the operational state of the above reproducing apparatus.
In the above proposed reproducing apparatus, the speed control with respect to the feeding (moving) of the above reproducing transducer including the reproducing element, in the radial direction of the disc upon the above described special reproduction modes, is performed by controlling the voltage applied to a D.C. motor used for driving and feeding the reproducing transducer as described above. However, this method is disadvantageous in that the speed varying range for performing reproduction at various speeds, cannot be set to a wide range. Furthermore, another method can be considered in which the meshing of gears are changed over to change over the transmitting speed to the reproducing transducer from the motor, according to the above operational modes. However, this method is disadvantageous in that the size of the whole apparatus becomes large, and the cost of the apparatus becomes high.